Carsten, Ctrl+0,M will only work when using a TFS 2012 server, as the My Work window will not show when connected to an older server. If you are connected to a TFS 2012 server, including tfspreview.com, and it doesn't work, let me know so that we can look into it.

Alt+V,E,S will open SCE via the View->OtherWindows menu out of the box. Since SCE is not a Team Explorer page, it doesn’t have one of the precious few Ctrl+0 rooted keys assigned to it. We are using those only for experiences inside Team Explorer.

There is a workaround, though. The user can bind the key of their choice for the View.TfsSourceControlExplorer command using Tools->Options->Keyboard.